Ride-hailing companies argue it's not, which is why they refuse to do it and are backing out of cities that try to make them. But security experts and public officials think otherwise.

Charles Carroll, a top executive in a company that helps governments run background checks, can hardly believe the debate about how best to screen drivers for Uber, Lyft and other car-hailing companies. It’s not the companies refusing to use fingerprint-based FBI background checks that surprises Carroll, it’s that the companies argue their screenings are better than fingerprinting.

“The fingerprint and the background search through the FBI is absolutely the gold standard,” he said. “I’ve never heard of anybody question this until Uber came along.”

Usually, the debate over whether to use fingerprints comes down to cost, said Carroll, the senior vice president of identity services at MorphoTrust. In Texas, for example, a one- or two-county criminal history search based solely on a person’s name and birthday would cost $3 or $4. In Texas, for a check with the FBI database, which covers the whole country, Carroll's company charges about $39.

But violent acts by Uber drivers, including a shooting spree in Kalamazoo, Mich., that left six people dead, have prompted calls in cities around the country for more outside scrutiny. Uber and Lyft, though, argue that their current system is safer than fingerprinting.

The issue is getting a lot of attention these days, particularly after voters in Austin, Texas, this weekend shot down a law proposed by ride-hailing companies to prohibit the city from fingerprinting Uber and Lyft drivers. The defeat for the companies, which spent at least $8.6 million backing the failed initiative, means drivers for ride-hailing companies there will have to undergo the same kind of background checks as cab drivers do, which includes submitting fingerprints to the city for an FBI search. Fifty-six percent of Austin voters opposed the measure, in what was easily the most expensive race in the history of the city.

After Saturday's vote, Uber and Lyft both said they would cease service in Austin starting Monday to avoid having to change the way they currently do business. Uber uses a company called Checkr to process background checks. Applicants provide their full name, date of birth, Social Security number and driver’s license number, among other things, and Checkr then runs that information through several databases, including sex offender registries and terrorist lists. The city never sees the results. Under Austin's new law, that would all have to change.

In the Austin campaign, the ride-hailing companies claimed one-third of Austin cab drivers who passed the city’s test didn’t pass Uber’s. That survey only looked at the 163 cab drivers (out of about 3,000 in the city) who also applied to drive for Uber. Uber hasn’t released many details about the survey, but the Austin American-Statesmen pointed out that it was taken before the Austin City Council expanded the scope of background checks for cab drivers from statewide to national FBI searches.

Only two other cities require fingerprint checks for ride-hailing drivers -- Houston andNew York City -- but there’s a push to do so in others, including Atlanta, Boston, Los Angeles and San Francisco. Uber has also threatened to leave Houston -- as Lyft already has -- if the city doesn’t repeal its fingerprinting requirements.

“Houston’s rules are some of the most burdensome in the country … [and] there is no evidence to suggest this improves safety for passengers,” wrote Sarfraz Maredia, Uber’s general manager in Houston, in a letter to city leaders.

Mayor Sylvester Turner, though, said Houston’s background checks found Uber-approved applicants who had histories of drunken driving, prostitution, assault and battery, and murder. One applicant had 24 aliases, five birthdates, 10 Social Security numbers and an active warrant for an arrest. He has also pointed out that Uber’s national checks don't include information from Delaware, Massachusetts, South Dakota and Wyoming.

“What I can tell you is that, if the city’s background checks protected even one person as it relates to public safety, it has been worth it,” the mayor said. “In this city, we cannot afford to compromise public safety.”

Uber also claims that Houston’s certification process took as long as four months for a two-year permit, and that 20,000 potential drivers screened by Uber opted not to go through the city screening process. Uber didn’t disclose how many drivers it has in Houston, and it went to court to block the city and state from releasing that information.

Turner disputes Uber’s charges, noting that 47 percent of drivers reported no delays, and two-thirds of them said they got their license in less than two weeks.

Uber also previously tried to discredit fingerprinting services. Because fingerprints can smudge or smooth with time, the company argues that makes them unreliable. In some cases, identifying fingerprints requires human input, which is subject to human error, the company wrote.

Carroll, the executive at the fingerprinting company, doesn’t buy it.

“You need to make sure that the person who has control over your safety and security has absolutely had an in-depth background search,” he said. “To me, there’s only one way to do that, and that’s through the FBI.”

Jails and prisons around the country are replacing in-person visits with video calls, enacting strict mail policies and other regulations that limit inmates' communication with family, friends and lawyers.